Rotary mixer and system and method thereof

ABSTRACT

A rotor assembly includes a generally cylindrical rotor having a drive end and a bearing end opposite to the drive end. The rotor is rotatable about a longitudinal axis. The rotor assembly further includes a transmission contained substantially within the rotor at the drive end. The transmission has an input shaft and an output shaft offset from the input shaft. The output shaft is operatively coupled to the rotor and is coaxial with the longitudinal axis of the rotor. The rotor assembly further includes a bearing assembly contained substantially within the rotor at the bearing end. The rotor assembly has a mounting axis and a bearing axis offset from the mounting axis. The bearing assembly further has a rotatable bearing operatively coupled to the rotor and is coaxial with the longitudinal axis of the rotor.

TECHNICAL FIELD

The present disclosure relates to rotary mixers and more particularly, to a rotor assembly for a rotor mixer.

BACKGROUND

Machines, such as road reclaimers, soil stabilizers and rotary mixers, have a rotor assembly for removing or mixing road surface and base materials such as, rock, asphalt, concrete, or soil. The rotor assembly typically includes a rotor having multiple cutting tools disposed on a peripheral surface thereof. The rotor is rotated through a suitable interface, e.g., a drive mechanism drawing power from an engine. During operation, the rotor rotates, causing the cutting tools to come in repeated contact with the road surface for cutting and/or mixing the road surface materials. Typically, a cutting depth created by the rotor is dependent upon a diameter of the rotor and ground clearance distance to the drive mechanism. In order to create a deeper cut, a diameter of the rotor may be required to be increased. However, increasing the diameter of the rotor can lead to a decrease in an amount of force generated by the cutting tools disposed on the peripheral surface of the rotor. As a result, productivity of the machine may be reduced.

U.S. Pat. No. 8,256,198, hereinafter the '198 patent, describes an automatically steered gearbox for controlling an implement with a pivoting tongue. According to the '198 patent, a mower is suspended from a frame and includes a header with a cutter. A tongue is pivotally connected to the mower frame and is moveable with respect to the frame by a hydraulic cylinder. At the front of the tongue a front gearbox is rigidly attached to the tongue. The front gearbox transmits rotary power from the power take off of the tractor to a rear gearbox pivotally attached to the header. Further, the rotary power from the rear gearbox, is passed on ultimately to the rotary cutting units. Pivoting of the rear gearbox is controlled by a steering connection operatively attached between the front and rear gearboxes.

SUMMARY OF THE DISCLOSURE

In one aspect of the present disclosure, a rotary mixer is provided. The rotary mixer includes a frame and a drive train journaled within a drive train housing pivotably mounted to the frame. The rotary mixer further includes a bearing housing pivotably mounted to the frame and a generally cylindrical rotor coupled to the bearing housing. The cylindrical rotor has a drive end and a bearing end opposite to the drive end. The cylindrical rotor is rotatable about a longitudinal axis of the rotor. The rotary mixer further includes a transmission contained within the rotor at the drive end and having an input shaft operatively coupled to the drive train. The transmission further includes an output shaft at an offset from the input shaft. The output shaft is operatively coupled to the rotor, and is coaxial with the longitudinal axis of the rotor. The rotary mixer further includes a bearing assembly contained within the rotor at the bearing end. The bearing assembly has a mounting axis and a bearing axis offset from the mounting axis. The bearing assembly is fixedly mounted around the mounting axis to the bearing housing. The bearing assembly has a rotatable bearing coaxial with the longitudinal axis of the rotor and is operatively coupled to the rotor.

In another aspect of the present disclosure, a rotor assembly for a rotary mixer is provided. The rotor assembly having a generally cylindrical rotor, having a drive end and a bearing end opposite to the drive end, being rotatable about a longitudinal axis of the rotor. The rotor assembly further includes a transmission contained substantially within the rotor at the drive end. The transmission has an input shaft and an output shaft offset from the input shaft. The output shaft is operatively coupled to the rotor and is coaxial with the longitudinal axis of the rotor. The rotor assembly further includes a bearing assembly contained substantially within the rotor at the bearing end. The rotor assembly has a mounting axis and a bearing axis offset from the mounting axis. The bearing assembly further has a rotatable bearing operatively coupled to the rotor and is coaxial with the longitudinal axis of the rotor.

In yet another aspect of the present disclosure, a rotary mixer is provided. The rotary mixer includes a frame and an engine mounted on the frame. The rotary mixer further includes a drive train journaled within a drive train housing pivotably mounted to the frame operatively coupled to the engine. The rotary mixer further includes a bearing housing pivotably mounted to the frame and a generally cylindrical rotor coupled to the bearing housing. The cylindrical rotor has a drive end and a bearing end opposite to the drive end. The cylindrical rotor is rotatable about a longitudinal axis of the rotor. The rotary mixer further includes a transmission contained within the rotor at the drive end and having an input shaft operatively coupled to the drive train. The transmission further includes an output shaft at an offset from the input shaft. The output shaft is operatively coupled to the rotor, and is coaxial with the longitudinal axis of the rotor. The rotary mixer further includes a mixing chamber coupled to the frame and at least partially surrounding the rotor, and a means for varying a height of the rotor above or below a ground surface. The rotary mixer further includes a bearing assembly contained substantially within the rotor at the bearing end. The bearing assembly has a mounting axis and a bearing axis offset from the mounting axis. The drive train housing and the bearing housing are attached to hydraulic cylinders that are coordinated to raise and lower the two housings together. The bearing assembly is fixedly mounted around the mounting axis to the bearing housing. The bearing assembly has a rotatable bearing coaxial with the longitudinal axis of the rotor and is operatively coupled to the rotor.

Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of the specification, are illustrative of one or more embodiments of the disclosed subject matter, and, together with the description, explain various embodiments of the disclosed subject matter. Further, the accompanying drawings have not necessarily been drawn to scale, and any values or dimensions in the accompanying drawings are for illustration purposes only and may or may not represent actual or preferred values or dimensions. Where applicable, some or all select features may not be illustrated to assist in the description and understanding of underlying features.

FIG. 1 is a side view of a rotary mixer, according to one or more embodiments of the present disclosure;

FIG. 2 is a schematic view of a rotor with an engine of the rotary mixer of FIG. 1, according to one or more embodiments of the present disclosure;

FIG. 3 is a perspective view of a rotor assembly for the rotor of FIG. 2, according to one or more embodiments of the present disclosure; and

FIG. 4 is a side view of the rotor assembly of FIG. 3, according to one or more embodiments of the present disclosure.

DETAILED DESCRIPTION

The description set forth below in connection with the appended drawings is intended as a description of various embodiments of the described subject matter and is not necessarily intended to represent the only embodiment(s). In certain instances, the description includes specific details for the purpose of providing an understanding of the described subject matter. However, it will be apparent to those skilled in the art that embodiments may be practiced without these specific details. In some instances, well-known structures and components may be shown in block diagram form in order to avoid obscuring the concepts of the described subject matter. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or the like parts.

Any reference in the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, characteristic, operation, or function described in connection with an embodiment is included in at least one embodiment. Thus, any appearance of the phrases “in one embodiment” or “in an embodiment” in the specification is not necessarily referring to the same embodiment. Further, the particular features, structures, characteristics, operations, or functions may be combined in any suitable manner in one or more embodiments, and it is intended that embodiments of the described subject matter can and do cover modifications and variations of the described embodiments.

It must also be noted that, as used in the specification, appended claims and abstract, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. That is, unless clearly specified otherwise, as used herein the words “a” and “an” and the like carry the meaning of “one or more. ” Additionally, it is to be understood that terms such as “left,” “right,” “top,” “bottom,” “front,” “rear,” “side,” “height,” “length,” “width,” “upper,” “lower,” “interior,” “exterior,” “inner,” “outer,” and the like that may be used herein, merely describe points of reference and do not necessarily limit embodiments of the described subject matter to any particular orientation or configuration. Furthermore, terms such as “first,” “second,” “third,” etc. merely identify one of a number of portions, components, points of reference, operations and/or functions as described herein, and likewise do not necessarily limit embodiments of the described subject matter to any particular configuration or orientation.

Generally speaking, embodiments of the present subject matter provide a rotor for a rotary mixer where the drive arrangement for the rotor has an input shaft that is offset from a longitudinal axis of the rotor. A bearing assembly is also provided on the rotor. The bearing assembly is operatively coupled to the rotor and has an offset mounting similar to that of the drive arrangement. The offset of the drive and bearing arrangements may allow the rotor to achieve increased cutting depth as compared to a rotor system without an offset arrangement.

Referring to FIG. 1, a side view of a machine 100 is illustrated, according to one or more embodiments of the present disclosure. The machine 100, according to one or more embodiments of the present disclosure may be a rotary mixer. It will be appreciated that the embodiments of the present disclosure can be similarly applied to other types of machines, such as, but not limited to, a road milling machine, a road reclaimer, a cold planer, and the like. The term machine, also interchangeably referred to as the “rotary mixer 100,” that can be used for milling a ground surface 102 for purposes, such as road construction. The rotary mixer 100 includes a frame 104 and an operator cab 106 mounted on the frame 104. The operator cab 106 may include control elements, such as a joystick, multiple control levers, multiple switches and the like, for controlling various operations of the rotary mixer 100.

The rotary mixer 100 includes a powertrain 108 having an engine 110, a gearbox (not shown) mounted on the frame 104, and ground engaging units 116. In one embodiment, the engine 110 is disposed at a front end 112 of the rotary mixer 100, as illustrated in FIG. 1. In another embodiment, the engine 110 may be disposed at a rear end 114 of the rotary mixer 100. In one embodiment, the engine 110 may be an internal combustion engine, an electric motor, power storage device including batteries, a hybrid engine, or a combination of two or more of the foregoing power sources. The engine 110 may include multiple cylinders defined in various configurations, such as a ‘V’ type configuration and an in-line configuration. The gearbox may be coupled to the engine 110 and the ground engaging units 116 for transmitting power generated by the engine 110 to the ground engaging units 116. The ground engaging units 116 may be configured to support the frame 104 on the ground surface 102, and also aid in propelling the rotary mixer 100 on the ground surface 102 in a desired direction and at a desired speed. In the illustrated embodiment, ground engaging units 116 may include wheels. In an alternative embodiment, the set of ground engaging units 116 may include tracks. In yet another embodiment, the set of ground engaging units 116 may include a combination of wheels and tracks. In one or more embodiments, the gearbox may have multiple gear drives to change a gear ratio.

In some embodiments, the powertrain 108 may include a generator to derive electric power from the power generated by the engine 110. In such a case, each of the ground engaging units 116 may be coupled to electric motors such that the electric motors get electrical power from the generator, and in turn propel the ground engaging units 116 on the ground surface 102.

In other embodiments, the powertrain 108 may include one or more hydraulic pumps. In some embodiments, each of the ground engaging units 116 may be coupled to hydraulic actuators (hydraulic motors, cylinders, etc.) such that the hydraulic actuators are driven from one or more of the hydraulic pumps, and in turn propel the ground engaging units 116 on the ground surface 102.

The rotary mixer 100 further includes a mixing chamber 118. In one or more embodiments, a width of the mixing chamber 118 may be equivalent to a width of the rotary mixer 100. In alternate embodiments, the width of the mixing chamber 118 may vary based on an operational requirement of the rotary mixer 100. Although the present disclosure is described with respect to the rotary mixer 100 having the mixing chamber 118 disposed between the front and rear ground engaging units 116, it will be appreciated by a person skilled in the art that the mixing chamber 118 may be disposed at one of the rear end 114 and the front end 112 of the rotary mixer 100 without limiting the scope of the present disclosure.

The mixing chamber 118 may be defined by a first side plate 120, a second side plate (not shown) opposite to the first side plate 120, an overhead plate (not shown) coupled to each of the first side plate 120 and the second side plate, a front door (not shown), and a rear door (not shown). Specifically, each of the first side plate 120, the second side plate, and the overhead plate are coupled to each other to define the mixing chamber 118. In one embodiment, each of the first side plate 120, the second side plate and the overhead plate may be coupled to each other using fasteners, such as nuts and bolts. In another embodiment, each of the first side plate 120, the second side plate, and the overhead plate may be welded to each other to form a single integrated structure. The front door and the rear door can be pivotably coupled to the overhead plate. Owing to the pivoted coupling, the front and rear doors may be opened and closed to selectively exit reclaimed material via one or more hydraulic actuators (not shown). In some embodiments, the mixing chamber 118 may be configured to move with respect to the frame 104 of the rotary mixer 100. Specifically, the mixing chamber 118 may be configured to tiltably move with respect to the frame 104 of the rotary mixer 100 between a lowered and raised position. In other embodiments, the mixing chamber 118 may be fixedly mounted to the frame 104.

The rotary mixer 100 may further include a drive train housing 122 pivotably mounted to the frame 104 of the rotary mixer 100. More specifically, a first end 124 of the drive train housing 122 may be pivotably coupled to the frame 104 of the rotary mixer 100. The drive train housing 122 may be coupled to the frame 104 in such a way that the drive train housing 122 can be pivoted about an axis A-A′ (shown in FIG. 2).

As shown in FIG. 2, the rotary mixer 100 may further include a bearing housing 128 opposite the drive train housing 122. The bearing housing 128 is pivotably mounted to the frame 104 of the rotary mixer 100. More specifically, a first end 130 of the bearing housing 128 is pivotably coupled to the frame 104 of the rotary mixer 100. The bearing housing 128 is coupled to the frame 104 in such a way that the bearing housing 128 can be pivoted about the axis A-A′.

Referring again to FIG. 1, the rotary mixer 100 may further include a means for varying the height of a rotor 202 and mixing chamber 118 above or below the ground surface 102. In a preferred embodiment, hydraulic cylinders 138 may be used for varying the height of the rotor 202 and mixing chamber 118 above the ground surface 102. The drive train housing 122 and the bearing housing 128 (shown in FIG. 2) may be attached to the hydraulic cylinders 138 and the hydraulic cylinders 138 may be coordinated to raise and lower each of the drive train housing 122 and the bearing housing 128 with respect to the ground surface 102. As such, the drive train housing 122 and the bearing housing 128 are pivoted on a common axis. More specifically, each of the drive train housing 122 and the bearing housing 128 may pivot about the axis A-A′ upon actuation and movement of the hydraulic cylinders 138. In an alternate embodiment, the rotor 202 and mixing chamber 118 may be raised or lowered via a pulley arrangement.

The rotary mixer 100 may include a hydraulic system 140 (shown in FIG. 1). In the illustrated embodiment, the hydraulic system 140 may be disposed adjacent to the front end 112 of the rotary mixer 100. In an alternative embodiment, the hydraulic system 140 can be disposed at any location on the machine 100. The hydraulic system 140 may include various components, such as a reservoir, one or more hydraulic pumps, one or more direction control valves, and other control valves, for supplying hydraulic fluid at a desired pressure to various operating systems of the rotary mixer 100. The various operating systems of the rotary mixer 100 may include, but is not limited to, the hydraulic cylinders 138 to raise or lower each of the drive train housing 122 and the bearing housing 128 and the hydraulic actuators to actuate the front and rear door of the mixing chamber 118. The one or more hydraulic pumps of the hydraulic system 140 may be operably coupled with the engine 110 to receive the power therefrom. Upon receiving the power from the engine 110, the one or more hydraulic pumps may supply the hydraulic fluid to the various operating systems of the rotary mixer 100 via hydraulic conduits (tubing, hoses, etc.).

As illustrated in FIG. 2, the rotor 202 may be operatively coupled to the engine 110, according to one or more embodiments of the present disclosure. The rotor 202 may be arranged within the mixing chamber 118. Specifically, the rotor 202 may be rotatably disposed within the mixing chamber 118. The rotor 202 may have a width slightly less than the width of the mixing chamber 118 to allow the rotor 202 to rotate about a longitudinal axis Y-Y′ (shown in FIG. 4) of the rotor 202 within the mixing chamber 118. The mixing chamber 118 at least partially surrounds the rotor 202 of the rotary mixer 100, as shown in FIG. 1. More specifically, the rotor 202 may be slidably coupled to the mixing chamber 118 such that the rotor 202 may be raised or lowered within the mixing chamber 118 and a portion of the rotor 202 may extend outward from the mixing chamber 118 by a selectable distance from a plane along the periphery of a bottom portion of the mixing chamber 118. In addition, the rotor 202 may have a diameter less than the height of the mixing chamber 118 so that adequate clearance is available for the rotor 202 to rotate within the mixing chamber 118.

The rotor 202 may be provided with multiple cutting tools 206. The multiple cutting tools 206 are disposed circumferentially along an outer surface 204 of the rotor 202, and extend outwardly from the outer surface 204. The cutting tools 206 may be detachably attached to the outer surface 204 of the rotor 202. The cutting tools 206 may be selected based on the operational requirement of the rotary mixer 100. A cutting plane of the rotary mixer 100 is tangential to the plane containing periphery of the bottom portion of the mixing chamber 118 and is parallel to a direction of travel of the rotary mixer 100.

The rotor 202 may have a drive end 208 and a bearing end 210 opposite the drive end 208. As mentioned previously, the rotary mixer 100 may have the drive train housing 122 and the bearing housing 128 pivotably mounted to the frame 104. The drive train housing 122 may be pivotably mounted adjacent to the drive end 208 of the rotor 202. A drive train 212 is journaled within the drive train housing 122. The drive train 212 is configured to receive power from the engine 110 and transfer the power to the rotor 202. In one embodiment, the engine 110 may be coupled to the drive train 212 via a coupling 214. In another embodiment, the engine 110 may be operatively coupled to the drive train 212 via a belt drive or other method known in the art. The bearing housing 128 is pivotably mounted adjacent to the bearing end 210 of the rotor 202. The bearing housing 128 is configured to house multiple bearings therein to reduce friction generated due to rotation of the rotor 202.

Referring to FIG. 3, a perspective view, and FIG. 4, a side view, of a rotor assembly 300 is respectively illustrated, according to one or more embodiments of the present disclosure. For the sake of description and illustration, the cutting tools 206 disposed on the outer surface 204 of the rotor 202 are not shown in FIGS. 3 and 4. The rotor assembly 300 has a generally cylindrical rotor 202, a transmission 302 and a bearing assembly 304. The rotor 202 may have a thickness defined between the outer surface 204 and an inner surface 306 of the rotor 202. The thickness of the rotor 202 may be dependent upon an axial force applied by the cutting tools 206 disposed on the outer surface 204 of the rotor 202 in order to effectively hold the cutting tools 206 on the rotor 202 during operation of the rotor 202. In some embodiments, the rotor 202 may include first ring 314 and second ring 328. First ring 314 and second ring 328 may be fixedly attached to the inner surface 306 of the rotor 202. In some embodiments, first ring 314 and second ring 328 may be welded to the inner surface 306 of the rotor 202.

In some embodiments, the transmission 302 of the rotor assembly 300 may include a first gear box 320, having a housing fixedly mounted around a mounting axis Z-Z′ to drive train housing 122. In some embodiments, the transmission 302 of the rotor assembly 300 may include a second gear box 322 fixedly mounted to second ring 328 of the rotor 202. In the embodiments illustrated in FIGS. 3 and 4, second gear box 322 may be mounted to second ring 328 using fasteners 330, such as bolts. In some embodiments, the first gear box 320 may be rotatably coupled to the second gear box 322 and then through, for example, a planetary gear arrangement contained within second gear box 322, to the housing of the second gear box 322. The housing of the second gear box 322 may therefore form an output shaft that is coaxial with the longitudinal axis Y-Y′ of the rotor 202 and drives rotor 202 through second ring 328.

The transmission 302 may be contained substantially within the rotor 202 at the drive end 208. In some embodiments, the transmission 302 is contained within the rotor 202 such that a portion of the transmission 302 lies outside the rotor 202 by a predetermined distance from a plane containing periphery of a first end 318 of the rotor 202. In other embodiments, the transmission 302 may be completely contained within the rotor 202.

In some embodiments, the transmission 302 of the rotor assembly 300 may be configured to transfer power from the drive train 212 (see FIG. 2) to the rotor 202 and rotate the rotor 202 at a predetermined speed. In some embodiments, the transmission 302 may be adapted to operate at one of a first predetermined speed and a second predetermined speed. The first predetermined speed and the second predetermined speed may be achieved through different gear ratios obtainable through the transmission 302. In order to convey the power from the drive train 212 to the rotor 202, the transmission 302 includes an input shaft 312 rotatably coupled to drive train 212.

Referring to FIG. 4, the input shaft 312 may be received within the first gear box 320 of transmission 302 such that the input shaft 312 is aligned coaxial with the mounting axis Z-Z′. The mounting axis Z-Z′ and the longitudinal axis Y-Y′ are positioned at an offset distance “O.”

In some embodiments, the rotor assembly 300 for the rotary mixer 100 may further include the bearing assembly 304 at the bearing end 210 of the rotor 202. The bearing assembly 304 may be fixedly mounted around the mounting axis Z-Z′ to the bearing housing 128. In one embodiment, the bearing assembly 304 may be fastened to the bearing housing 128 via fasteners, such as nuts and bolts. In another embodiment, the bearing assembly 304 may be welded to the bearing housing 128. The bearing assembly 304 may be contained substantially within the rotor 202 at the bearing end 210. In some embodiments, the bearing assembly 304 may be contained within the rotor 202 such that a portion of the bearing assembly 304 lies outside the rotor 202 by a predetermined distance from an imaginary plane containing periphery of a second end 332 of the rotor 202. In other embodiments, the bearing assembly 304 may be completely disposed within the rotor 202.

The bearing assembly 304 may include a shoulder portion 334 and a neck portion 336 defined at a distance from the shoulder portion 334. The shoulder portion 334 of the bearing assembly 304 may be defined along the mounting axis Z-Z′ of the bearing assembly 304 and the neck portion 336 may be defined along a bearing axis B-B′ of the bearing assembly (shown in FIG. 4). The bearing axis B-B′ of the neck portion 336 is defined at an offset from the mounting axis Z-Z′. In the embodiments illustrated in FIGS. 3 and 4, neck portion 336 may be mounted to first ring 314 using fasteners 340, such as bolts.

The bearing assembly 304 may have a rotatable bearing (not shown) coupled to the neck portion 336 of the bearing assembly 304. The rotatable bearing may be disposed along the bearing axis B-B′ of the bearing assembly 304 and, as such, may be aligned coaxial with the longitudinal axis Y-Y′ of the rotor 202. In the illustrated embodiment, the rotatable bearing may be contained within shoulder portion 334 of bearing assembly 304.

INDUSTRIAL APPLICABILITY

The present disclosure relates to the rotor assembly 300 for the rotary mixer 100. The rotor assembly 300 includes the rotor 202 having a generally cylindrical shape, the transmission 302, and the bearing assembly 304. When using the rotary mixer 100, the power generated by the engine 110 is transferred to the drive train 212 of the rotary mixer 100 via the coupling 214. As the drive train 212 is operably coupled to the input shaft 312 of the transmission, the input shaft 312 begins to rotate, and further transfers the rotational motion, through the transmission 302, to the rotor 202. The rotational motion of the rotor 202 causes the rotatable bearing within the bearing assembly 304 to rotate. The rotor 202 may rotate at one of the first predetermined speed and the second predetermined speed as selected by the operator. The bearing assembly 304 aids in maintaining the speed of the rotor 202, and also reducing the friction generated by the rotor 202 during rotation. The engine 110 of the rotary mixer 100 also supplies the power to the ground engaging units 116 and thereby propels the rotary mixer along the ground surface 102.

Further, during operation of the rotary mixer 100, the operator of the rotary mixer 100 may actuate the hydraulic cylinders 138 to lower or raise the rotor 202 with respect to the frame 104. As such the cutting tools 206 of the rotor 202 can be brought into contact with the ground surface 102. An extent of such lowering of the rotor 202 may be determined on the basis of a cutting depth required, and dimension or type of the cutting tools 206 attached to the outer surface 204 of the rotor 202. In some embodiments, the mixing chamber 118 may also be lowered and raised along with the rotor 202. In other embodiments, the mixing chamber 118 may be fixedly attached to the frame 104.

As the rotor 202 rotates, the cutting tools 206 come in repeated contact with the ground surface 102 to break up a layer of material from the ground surface 102 to form the reclaimed material. The reclaimed material is held within the mixing chamber 118 and the operator may actuate the one or more hydraulic actuators to open or close one of the front door and the rear door to selectively exit the reclaimed material. On completion of the operation, the operator may raise the rotor 202 by actuating the hydraulic cylinders 138.

The transmission 302 provides an offset from the input shaft 312 to the longitudinal axis Y-Y′ of the rotor 202. This offset may provide a greater clearance between the cutting tools 206 of the rotor 202 and the drive train housing 122 and the bearing housing 128.

While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof. 

What is claimed is:
 1. A rotary mixer comprising: a frame; a drive train journaled within a drive train housing pivotably mounted to the frame; a bearing housing pivotably mounted to the frame; a generally cylindrical rotor having a drive end and a bearing end opposite the drive end, the rotor being rotatable about a longitudinal axis; a transmission contained substantially within the rotor at the drive end and having an input shaft operatively coupled to the drive train and having an output shaft, offset from the input shaft, coaxial with the longitudinal axis of the rotor and wherein the output shaft is operatively coupled to the rotor; and a bearing assembly contained substantially within the rotor at the bearing end and having a mounting axis and a bearing axis, offset from the mounting axis, wherein the bearing assembly is fixedly mounted around the mounting axis to the bearing housing, and wherein the bearing assembly has a rotatable bearing coaxial with the longitudinal axis of the rotor and operatively coupled to the rotor.
 2. The rotary mixer of claim 1, wherein the transmission is adapted to operate at one of a first predetermined speed and a second predetermined speed.
 3. The rotary mixer of claim 1 further comprising a mixing chamber coupled to the frame and at least partially surrounding the rotor.
 4. The rotary mixer of claim 1 further comprising a plurality of traction units configured to support the frame on a ground surface.
 5. The rotary mixer of claim 1 further comprising an engine mounted on the frame and operatively coupled to the drive train.
 6. The rotary mixer of claim 1 further comprising a means for varying the height of the rotor above or below a ground surface.
 7. The rotary mixer of claim 1, wherein the rotor is provided with a plurality of cutting tools.
 8. The rotary mixer of claim 1, wherein the drive train housing and the bearing housing are attached to hydraulic cylinders, the hydraulic cylinders are coordinated to raise and lower each of the drive train housing and the bearing housing together.
 9. A rotor assembly for a rotary mixer, the rotor assembly comprising: a generally cylindrical rotor having a drive end and a bearing end opposite the drive end, the rotor being rotatable about a longitudinal axis; a transmission contained substantially within the rotor at the drive end and having an input shaft and an output shaft, offset from the input shaft, wherein the output shaft is coaxial with the longitudinal axis of the rotor and wherein the output shaft is operatively coupled to the rotor; and a bearing assembly contained substantially within the rotor at the bearing end and having a mounting axis and a bearing axis, offset from the mounting axis, wherein the bearing assembly has a rotatable bearing coaxial with the longitudinal axis of the rotor and operatively coupled to the rotor.
 10. The rotor assembly of claim 9, wherein the transmission is adapted to operate at one of a first predetermined speed and a second predetermined speed.
 11. The rotor assembly of claim 9 further comprising a mixing chamber coupled to the frame and at least partially surrounding the rotor.
 12. The rotor assembly of claim 9 further comprising an engine mounted on a frame and operatively coupled to the drive train
 13. The rotor assembly of claim 9 further comprising a plurality of traction units configured to support the frame on a ground surface.
 14. The rotor assembly of claim 9 further comprising a drive train journaled within a drive train housing pivotably mounted to the frame and a bearing housing pivotably mounted to the frame.
 15. The rotor assembly of claim 9 further comprising a means for varying the height of the rotor above or below a ground surface.
 16. The rotor assembly of claim 9, wherein the drive train housing and the bearing housing are attached to hydraulic cylinders, the hydraulic cylinders are coordinated to raise and lower each of the drive train housing and the bearing housing together.
 17. A rotary mixer, comprising: a frame; an engine mounted on the frame; a drive train journaled within a drive train housing pivotably mounted to the frame and operatively coupled to the engine; a bearing housing pivotably mounted to the frame; a generally cylindrical rotor having a drive end and a bearing end opposite the drive end, the rotor being rotatable about a longitudinal axis; a transmission contained substantially within the rotor at the drive end and having an input shaft operatively coupled to the drive train and having an output shaft, offset from the input shaft, coaxial with the longitudinal axis of the rotor and wherein the output shaft is operatively coupled to the rotor; a mixing chamber coupled to the frame and at least partially surrounding the rotor; a means for varying a height of the rotor above or below a ground surface; and a bearing assembly contained substantially within the rotor at the bearing end and having a mounting axis and a bearing axis, offset from the mounting axis, wherein the bearing assembly is fixedly mounted around the mounting axis to the bearing housing, and wherein the bearing assembly has a rotatable bearing coaxial with the longitudinal axis of the rotor and operatively coupled to the rotor.
 18. The rotary mixer of claim 17, wherein the transmission is adapted to operate at one of a first predetermined speed and a second predetermined speed.
 19. The rotary mixer of claim 17, wherein the rotor is provided with a plurality of tools.
 20. The rotary mixer of claim 17, wherein the drive train housing and the bearing housing pivot on a common axis. 